An adhesives researcher tests the holding power of a wood glue under different humidities. He glues together small pieces of wood and randomly assigns each one to sit for an hour in a room with either 10%, 30%, 50%, 70%, or 90% relative humidity. Each glued piece of wood is then tested to see how many pounds of weight it takes to break the glue bond.

Select the appropriate statistical test from

(a) Single-sample z test;

(b) Single-sample t test;

(c) Independent-samples t test;

(d) Paired-samples t test;

(e) Between-subjects, one-way ANOVA; or

(f) None of the above.